This invention relates to methods and apparatus for stacking ingots of metal cast continuously by an automatic casting apparatus, and more particularly to a method and apparatus for automatically arranging such ingots into groups of predetermined arrangements and stacking the ingot groups in alternate tiers.
A continuous casting apparatus is widely used presently for continuously casting a nonferrous metal such as zinc into ingots. In the continuous casting apparatus, the metal in molten form is cast into a multiplicity of molds carried by an endless chain conveyor, and while moving the chain conveyor, dust or scum floating on the surface of the molten metal cast into the molds is removed and, at the same time, the metal cast into the molds is cooled to obtain ingots. A plurality of ingots thus cast by the continuous casting apparatus are grouped into an ingot group (referred to hereinafter as a stack unit) in which such ingots are arranged to form a horizontal layer, and a predetermined number of such stack units are stacked in tiers and tied together by a metal wire or band to constitute a stack of predetermined weight. The stack thus formed is then transported to the delivery or stored in a warehouse. However, difficulty is encountered in successfully tying the stack, and dangerous sliding movement of the ingots relative to one another in the stack may occur during transportation, when a plurality of ingots delivered from the molds carried by the chain conveyor are merely grouped into the stack unit, and a predetermined number of such stack units are merely stacked in tiers to constitute the stack of predetermined weight.
A method of alternately stacking two kinds of ingot groups of different patterns in tiers has been proposed in an effort to provide a stack consisting of stack units in which the ingots can be grouped into the respective patterns with a minimum of grouping steps while avoiding dangerous relative sliding movement of the ingots in the stack during tying and transportation. According to this proposed method, ingots are grouped to constitute two kinds of stack units each consisting of four ingots arranged in patterns A and B as shown in FIGS. 1e and 1f respectively. In the pattern A shown in FIG. 1e, the four ingots are arranged in two parallel rows in each of which the two ingots are longitudinally aligned, while in the pattern B shown in FIG. 1f, two of the four ingots are arranged in longitudinally parallel relation, and the remaining two are arranged in longitudinally normal relation to the longitudinal direction of the former ingots on opposite sides thereof.
The ingots have hitherto been grouped into the patterns A and B by the manual, and various studies have been made in an effort to automatically group the ingots into such patterns mechanically instead of manually. However, this automatic mechanical grouping has not yet been proved fully successful because a gap is inevitably produced between the ingots during grouping by mechanical means resulting in difficulty of sufficiently securely tying the ingots. A conveying machine such as a fork lift is generally used especially when the ingots tied together are conveyed by or loaded on or unloaded from vehicles or railway cars. In such a case, a stack consisting solely of plain ingots as shown in FIGS. 1c and 1d is difficult to be conveyed by the conveying machine, and the lowermost layer of the stack must be composed of legged ingots as shown in FIGS. 1a and 1b so that the stack can be successfully conveyed. In other words, the legged ingots must be disposed with their legs directed downward to constitute the lowermost layer of the stack, and the plain ingots must then be stacked in tiers on the lowermost layer. Therefore, in order to tie together the stacked ingots, the legged ingots must be arranged in either the pattern A or the pattern B, and then, the plain ingots arranged according to the patterns A and B must be stacked in alternate tiers on the legged ingots constituting the lowermost layer of the stack.
However, the ingots must be tied together by an automatic tying machine at a rate which corresponds to the rate of casting the ingots by the continuous casting apparatus, because an undesirable reduction in the ingot casting efficiency is inevitably given rise to when the rate of tying the ingots is less than the rate of casting the ingots by the continuous casting apparatus. It has become necessary, therefore, to suitably modify or improve the automatic tying machine so that the ingots can be tied together at the rate corresponding to the rate of casting the ingots by the continuous casting apparatus. Further, the prior art method used for stacking the ingots in tiers has been defective in that the factors including the inevitable formation of the gap between the grouped ingots result in dangerous relative sliding movement of the ingots during tying or transportation.